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Python is an interpreted programming language and claims to be a very effective programming language. Python was develop from Guido van Rossum. The name Python is based on the the TV show "Monty Python’s Flying Circus". Key features of Python are:

During execution the Python source code is translated into byte-code which is then interpreted by the Python interpreter. Python source code can also run on the Java Virtual Machine, in this case you are using Jython.

Python follows a different way then other programming languages to identify blocks. A block is identified by indentation. If you have an if statement and the next line is indented then it means that it a block belonging to the if. The most "pythonic" way is to use 4 spaces per indentation level. The Python interpreter will however recognize spaces or tabs. The only gottcha is you must never mix spaces and tabs,

The Python interpreter supports spaces or tabs. The most "pythonic" way is to use 4 spaces per indentation level. You can use either tab or space, but never use/mix both.

Download Python from http://www.python.org . Download version 2.6.x from Python. If you are using Windows you are getting a native installer for Python.

The following assume that you have already Eclipse installed. For an installation description of Eclipse please see Eclipse IDE for Java .

For Python development under Eclipse you can use the PyDev Plugin. PyDev is an active developed open source project. Install PyDev via the update manager via the following update site. http://pydev.org/updates . See Eclipse update manager for using the update manager.

The following create a single line comment.

				
# This is a comment
			

Python provides dynamic typing of its variables, e.g. you do not have to define a type of the variable Python will take care of this for you.

				
# This is a text
s= "Lars"
# This is an integer
x = 1
y=4
z=x+y
			

Python provides assertions. These assertions are always called.

				
assert(1==2)
			

Python allows to define methods via the keyword def. As the language is interpreted the methods need to be defined before using it.

				
def add(a,b):
    return a+b

print add(1,2)

			

The following demonstrates a loop the usage of an if-clause.

				
i = 1
for i in range(1, 10):
    if i <= 5 :
        print 'Smaller or equal then 5.\n',
    else:
        print 'Larger then 5.\n',

			

Python allows the following String operations.

For example:

				
s = "abcdefg"
assert (s[0:4]=="abcd")
assert ( s[4:]=="efg")
assert ("abcdefg"[4:0]=="")
assert ("abcdefg"[0:2]=="ab")
			

Python does not allow to concatenate a string directly with a number. It requires you to turn the number first into a string with the str() function.

If you don't use str() you will get "TypeError: cannot concatenate 'str' and 'int' objects".

For example:

				
print 'this is a text plus a number ' + str(10)

			

The following example is contained in the project "de.vogella.python.files".

The following reads a file, strips out the end of line sign and prints each line to the console.

				
'''
Created on 07.10.2009

@author: Lars Vogel
'''

f = open('c:\\temp\\wave1_new.csv', 'r')
print f
for line in f:
    print line.rstrip()
f.close()
			

The following reads the same file but write the output to another file.

				
'''
@author: Lars Vogel
'''

f = open('c:\\temp\\wave1_new.csv', 'r')
output = open('c:\\temp\\sql_script.text', 'w')
for line in f:
    output.write(line.rstrip() + '\n')
f.close()
			

The following example is contained in the project "de.vogella.python.files". It reads to files which contain one long comma separated string. This string is splitted into lists and the lists are compared.

				
f1 = open('c:\\temp\\launchconfig1.txt', 'r')
s= ""
for line in f1:
    s+=line
f1.close()

f2 = open('c:\\temp\\launchconfig2.txt', 'r')
s2= ""
for line in f2:
    s2+=line
f2.close()
list1 = s.split(",")
list2 = s2.split(",");
print(len(list1))
print(len(list2))


difference = list(set(list1).difference(set(list2))) 

print (difference)

			

The following is a defined class in Python. Python uses the naming convension __name__ for internal functions.

Python allows operator overloading, e.g. you can define what the operator + will to for a specific class.

The empty object (null) is called "None" in Python.

				
class Point:
    def __init__(self, x=0, y=0):
        self.x = x
        self.y = y
    def __str__(self):
        return "x-value" + str(self.x) + " y-value" + str(self.y)
    def __add__(self,other):
        p = Point()
        p.x = self.x+other.x
        p.y = self.y+other.y
        return p
        
p1 = Point(3,4)
p2 = Point(2,3)
print p1
print p1.y
print (p1+p2)